In a hybrid motor vehicle, the power plant is equipped with a heat engine and at least one electric motor, so that several distinct transmission modes can be implemented by a transmission device of this power plant, in order to couple one or more of these engines/motors with the driving wheels of the vehicle.
First of all, it is possible to choose to couple only one of these two engines/motors, or both engines/motors, with the driving wheels of the vehicle, and in fact, for each one of these engines/motors, with a gear ratio that is specific to it.
In a hybrid transmission mode, for example, the heat engine as well as the electric motor are coupled with the driving wheels of the vehicle. In such a hybrid transmission mode, the heat engine and the electric motor can therefore both contribute to propelling the vehicle, in particular when high torque must be exerted at the wheels of the vehicle. The heat engine can also, in such a hybrid transmission mode, provide this propulsion alone, while the electric motor remains coupled with the driving wheels in order to recharge the electric battery intended to power it.
In contrast, in a transmission mode corresponding to all electric functioning, only the electric motor is coupled with the driving wheels of the vehicle. This all electric transmission mode is particularly advantageous in braking phase. In effect, in this case, the kinetic energy of the vehicle can be recovered at least partially in electrical form by means of the electric motor, while the heat engine is uncoupled from the wheels of the vehicle and consumes no energy.
On the other hand, when the heat engine and the electric motor are both coupled with the driving wheels of the vehicle, the torque to produce in order to satisfy the torque demand from the driver can be shared, in variable proportions, between these two engines/motors.
Among the different transmission modes that can therefore be used, the transmission mode to implement is generally selected according to the functioning conditions of the vehicle, so as advantageously to minimize the energy consumption of this vehicle.
But such a selection of the transmission mode, based only on minimizing energy consumption, can bring about particularly frequent changes of transmission mode, which is annoying for the users of the vehicle and is not accompanied by any substantial reduction of the energy consumption of the vehicle.
In order to resolve this problem, a method is known in particular from document FR3014062 for energy management in a hybrid motor vehicle, in which the transmission mode to implement is chosen so as to minimize a mixed quantity of energy, which is the sum of a quantity of energy representing the energy consumption of the vehicle plus an annoyance value taking into account the annoyance of a change of transmission mode for the users of the vehicle, this method making it possible to limit the frequency of such changes of transmission mode.
But, when such a management method is used, inappropriate changes of transmission mode can persist, in particular rapid sequences of changes of transmission mode, during which the vehicle changes transmission mode for a very brief period, which is not accompanied by any substantial energy saving.